/**
 * Copyright (c) 2009 Noel Ang
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */
package com.lunarshades.samsara.logging;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.TimeZone;

/**
 * Logger implementation whose outlet for consumed events is a {@link
 * StringBuffer}. Events are each rendered into the buffer in the following
 * format.
 * <pre>
 * DDD:HH:MM MSG NL
 * </pre>
 * where: DD is the day of the year; HH is the hour of the day (24-hour format);
 * MM is the minute of the hour; MSG is the message specific to the {@link
 * Loggable Loggable} events consumed; and NL is the newline character
 * sequence.
 *
 * @author Noel Ang, sparta.variable@gmail.com
 * @see Loggable
 */
public class StringBufferLogger extends Logger {

public StringBufferLogger() {
    mBuffer = new StringBuffer();
    mDateTimeFormatter = new SimpleDateFormat("DDD:HH:mm");
    mIsDisposed = false;
}

@Override
public String toString() {
    return mBuffer.toString();
}

/**
 * Consume the specified event.
 *
 * @param event A Loggable object.
 *
 * @throws IllegalStateException if {@link #dispose()} has been previously
 *                               invoked.
 */
public void log(Loggable event) {
    if (!mIsDisposed) {
        if (event == null) {
            return;
        }
        Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("GMT-0"));
        String time = mDateTimeFormatter.format(calendar.getTime());
        Object message = event.message();
        synchronized (mBuffer) {
            mBuffer.append(time).append(SPACE).append(message).append(NEWLINE);
        }
    } else {
        throw new IllegalStateException("Object already disposed.");
    }
}

/**
 * Decides if the specified event is fit for consumption.
 *
 * @param event The event whose suitability is to be determined.
 *
 * @return True if the specified event would cause a subsequent call to the
 *         implementation's {@link #log(Loggable)} to be meaningful; false
 *         otherwise.
 */
public boolean accept(Loggable event) {
    return event != null;
}

/**
 * Discard the logger instance. This method provides a chance for an
 * implementation to free up resources. Once this method is called the object
 * should no longer be used; its behaviour after that point is undefined.
 */
public void dispose() {
    mIsDisposed = true;
}

private final StringBuffer mBuffer;
private final DateFormat mDateTimeFormatter;
private volatile boolean mIsDisposed;
}
